Thursday, April 23, 2009

NOTA BIOLOGI TINGKATAN 5

Hypertension (High Blood Pressure)

Definition

·systolic blood pressure is consistently over 140 (systolic is the "top" number of your blood pressure measurement, which represents the pressure generated when the heart beats)

·diastolic blood pressure is consistently over 90 (diastolic is the "bottom" number of your blood pressure measurement, which represents the pressure in the vessels when the heart is at rest)

Either or both of these numbers may be too high.

Pre-hypertension is when your systolic blood pressure is between 120 and 139 or your diastolic blood pressure is between 90 and 99 on multiple readings. If you have pre-hypertension, you are likely to develop high blood pressure at some point. Therefore, your doctor will recommend lifestyle changes to bring your blood pressure down to normal range.

Overview, Causes, & Risk Factors

Blood pressure is determined by the amount of blood pumped by the heart, and the size and condition of the arteries. Many other factors can affect blood pressure, including volume of water in the body; salt content of the body; condition of the kidneys, nervous system, or blood vessels; and levels of various hormones in the body.

·"Essential" hypertension has no identifiable cause. It may have genetic factors and environmental factors, such as salt intake or others. Essential hypertension comprises over 95% of all high blood pressure.

·"Secondary" hypertension is high blood pressure caused by another disorder. This may include:

·adrenal gland tumors

·kidney disorders

·use of medications, drugs, or other chemicals

·oral contraceptives

Hypertension Symptoms & Signs

Usually, no symptoms are present. Occasionally, you may experience a mild headache. If your headache is severe, or if you experience any of the symptoms below, you must be seen by a doctor right away. These may be a sign of dangerously high blood pressure (called malignant hypertension) or a complication from high blood pressure.

Hypertension Treatment

The goal of treatment is to reduce blood pressure to a level where there is decreased risk of complications. Treatment may occur at home with close supervision by the health care provider, or may occur in the hospital.

Medications may include diuretics, beta-blockers, calcium channel blockers, angiotensin-converting enzyme (ACE) inhibitors, angiotensin receptor blockers (ARBs), or alpha blockers. Medications such as hydralazine, minoxidil, diazoxide, or nitroprusside may be required if the blood pressure is very high.

Have your blood pressure checked at regular intervals (as often as recommended by your doctor.)